Hi Hendrick C
I’m sorry you and your pup are going through this! Seizures have many different causes and the first thing I would do is get a complete blood panel and a physical exam for your Shih-tzu ASAP.
Regarding flea and tick meds I would NOT use ANY of the edible or spot-ons (topical). Frontline, Advantage, Revolution, Sentinel, Nexguard, ALL contain NEUROTOXINS. They work by affecting the nervous systems of the offending insect and causing paralysis and death. They have definitely caused seizures in dogs. The theory is that Mammals (dogs and humans) are much less affected by these chemicals than insects are. But humans and dogs are affected they just don’t immediately drop dead as the insects do.
I would switch to a “greener” and more “holistic” approach to insect control. There are essential oils with a much lower chance of toxicity than the neurotoxins that work at repelling and eliminating fleas and ticks. There are boric acid and diatomaceous earth options for indoor flea and tick control and beneficial nematode options for outdoor flea and tick control.
I wish you and your pup the best!!!
